Spray drying method and apparatus



1 I N. c. FISCHER 2,292,512

SPRAY DRYING METHOD- AND 'APPARATUS Filed Sept. 2, 1939 2 Sheets-Sheet l Aug. 11, 1942. 2 N. c. FISCHER smm DRYING METHOD'AND APPARATUS 2 Shee ts-Sheet 2 Filed Sept. 2, 1939 five-722 07! J6 I sta Aug. 11, 1942 2,292,512 SPRAY DRYING METHOD AND APPARATUS tion oi Illinois Norman C. Fischer, Springfield, Mo., assignor to Armour and Company, Chicago, 111., a corpora- V Application September 2, 1939, Serial No. 298.20:

This invention relates to a spray drying method and apparatus suitable for use in drying liquids and semi-liquids such as milk, eggs, etc. In the spray drying of materials, such as for example, eggs, a primary objective has been to provide a maximum of contact between the particles and the drying medium. Various methods and apparatus have been employed but none have succeeded in this regard. In practically all such operations, the liquid has been sprayed directly from the nozzle into a drying chamber filled with heated air, the incoming stream of air being brought adjacent the material as it leaves the nozzle.

An object of the present invention is to pro-' vide a method and means for causing the sprayed material and the drying medium to travel together a desired distance after the spraying operation so as to produce a maximum of contact between the sprayed particles and the medium. A further object, is to providesimple and inexpensive means whereby a rotating column of drying medium contacts and proceeds in intimate I contact with the particles thrown out from the "spray nozzle,- the mixture of medium and particles being then discharged into an enlarged drying chamber. A still further object is to provide in combination an apparatus for delivering a wide angle cone of spray into which is brought a column of heated air, the sprayed particles'and air being carried together a distance beyond the nozzle to provide for their intimate mixture. Other specific objects and advantages will apspear as the specification proceeds.

The invention is illustrated, in a preferred em- ;bodiment, by the accompanying drawings, in

which Figure l is a transverse section view of apparatus embodying my invention, the section being "taken as indicated at line I, of Fig. 2; Fig. 2, a broken vertical section view, the section being taken as indicated at line 2 of Fig. 1'; Fig. 3, a broken, enlarged and part section view of the conduit for the heated air or drying medium; and Fig. 4, an enlarged detailed section view, the section being taken as indicated at line 4 of -Fig. 3.

In the illustration given, A designates a casing providing a drying chamber; B, a conduit for the introduction of heated air or other suitable drying medium; and C, a nozzleequipped spray pipe through which the eggs or other material is sprayed to form the particles to be dried.

in detail. The casing provides a cone shaped bottom structure ll equipped with a valve-controlled material discharge outlet II. The upper portion oi the casing A provides the usual bag I compartments l2, each beingprovided with a bag It, as illustrated at one side or the apparatus in Fig. 2. The inner side of each compartment is formed by the central drying chamber casing II. A reduced, pressure draw-oil pipe I! is provided above the bag compartments, as illustrated in Fig. 2, for drawing away the drying medium.

The bags I: may be of any suitable size or number. For example, twenty-five eight-inch diameter bags per house have been used with good results. I

The drying medium conduit 13 may also be of any suitable form or construction. In the illustration given, the conduit B enters the coneshaped portion ID of the casing and extends vertically, being supported by the spider bracket I. The conduit Bis provided with double walls I1 and I8 between which is placed a heat-insulating material It. The upper end portion of the wall I1 is tapered at 22 toward the discharge end of the conduit. There is thus provided a narrowed or tapered point end at the place where the heated air is discharged.

The spray pipe C enters the cone-shaped portion III of the casing A-and also extends in sealing relation through the double walled conduit B. The inner end of the pipe C is turned upwardly at 2| to provide a terminal which extends vertically and centrally within the"--conduit B. Upon the vertical portion 2| is mounted a vertical nozzle member 22 which may be of any suitable construction but which preferably is of the structure shown and claimed in my co-pending application, Serial No. 273,311, for nozzle. This type of nozzle forms a relatively wide angle cone of spray, enabling it to be brought into quick and v wide contact with the rising column of heated air.

The casing apparatus A is of old and wellknown construction and need notbe described In order'to produce a rotating column of heated air or other drying medium, I secure within the conduit B and below the nozzle 22 an inclined vane structure 22. The inclination of the vanes, asshown in Figs. 3 and 4, causes the rising column of air to whirl and thus widen the cone or spray particles. The whirling motion of the air 'further increases the travel of the particles and air above the nozzle.

In the structure described, it will be observed that the conduit 13 is extended well above the nozzle -22.' In one structure which has been used, the extension has been about 3 or 4 feet and the travel. of the hot air and spray through nozzle.

desired pressure, the material being thrown out by the nozzle in a wide angle cone and in the form of minute .particles. The column of heated air forced through the conduit B is given a rotating motion by the vanes 23 just below the nozzle 22 and the rotating air contacts the minute particles, traveling with the particles through the extensionof the conduit above the In this travel, a very intimate mixture of the heated air and sprayed particles is produced and the mixture thus formed isdischarged I from thetapered upper end of the conduit into the enlarged drying chamber where the drying medium expands 'and the dried particles drop toward the lower portion of the casing. The escape of the drying medium through the usual pipe l5 causes the particles to collect within the bags and the dried particles gradually flnd their way downwardly into the cone receptacle at the bottom of the casing. The dried product is discharged through the outlet ll into suitable containers.

The added apparatus is extremely simple and inexpensive but it provides a far more effective method and means of drying materials than heretofore used, while employing the same amount of drying medium, the drying operation being carired out, however, in less time.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, it being understood that many changes may be made in the details of construction and method spirit of the invention.

I claim:

1. In drying apparatus of the character set forth, a casing providing a chamber, said casing having an air outlet and a material outlet, an

without departing from the enlarged heated air conduit extending upwardly a substantial distance within said chamber, a liquid spray pipe extending into said chamber and also into said conduit, and a spray nozzle carried by said spray pipe, said conduit having insulated walls extending substantially vertically above said nozzle, the outer wall tapering inwardly toward the inner wall at the upper end of said conduit.

2. In drying apparatus of the class set forth. a casing providing a chamber, ,said casing having an outlet for the drying medium and for the dried product, a small conduit extending into said chamber with the top of the conduit opening upwardly into the central portion of the chamber and being spaced from the upper wall of the chamber by a distance equal to at least half of theheight of the chamber, a liquid spray pipe extending into said chamber and also centrally within said conduit, a discharge nozzle communicating with the end of said spray pipe and supported substantially below the outlet end of said conduit, the diameter of said conduit above said nozzle being substantially the same as the diameter of said conduit below said nozzle, said conduit having an insulated wall extending substantially vertically above said nozzle, one of the opposed surfaces of the insulated wall being tapered inwardly towards the other surface at the upper end of the conduit.

3. In drying apparatus of the character set forth, a casing providing a chamber, a conduit extending into said chamber with the top of the conduit opening upwardly in the central portion of the chamber, means for providing within the conduit a mixture of drying medium and material to be dried, means for discharging said mixture upwardly at a substantial velocity from the opening in the top of said conduit, said conduit having an insulated wall extending substantially vertically within the chamber, one of the opposed surfaces of said wall being tapered inwardly towards the other surface at the upper end of the conduit NORMAN C. FISCHER. 

